Concrete cutting machines

ABSTRACT

A machine (10) for cutting concrete paving or like material is provided having a support frame structure (12), front and rear wheels (14 and 16) and a rotatable cutting blade (20). A pair of auxiliary wheels (32) are also provided between the front and rear wheels on a transverse axle (34) which is pivotally movable relative to the support frame structure (12) about a transverse shaft (30). In an operative position for cutting concrete the front wheels (14) are in engagement with the ground and the auxiliary wheels (32) raised above the ground. Subsequent pivotal movement of the axle (34) relative to the support frame structure (12) about axle (30) lowers the auxiliary wheels (32) into contact with the ground and raises the front wheels (14) above the ground so that the forward part of the support structure (12) is supported by the auxiliary wheels (32) when the machine is out of the cutting mode. The pivotally movable auxiliary wheels (32) provide greater ease of maneuverability out of the cutting mode. The operator can lift the rear wheels (16) off a pavement by means of handles (51) provided at the rear of the machine and realign the machine as required for the next cut. The front wheels (12) are disposed at a forward position close to the cutting blade (20) to provide greater stability in the cutting mode.

This invention relates to machines for cutting or sawing concrete pavingor like materials such as asphalt, of the type comprising at least onecutting blade, means for driving the cutting blade and a wheeled supportstructure for supporting the cutting blade and its drive means. Suchmachines will hereinafter be referred to as "concrete cutting machines".

The invention is particularly concerned with concrete cutting machinesof the kind which are adapted to be used by one person who operates andmanoeuvres the machine from its rear as it moves forwardly with arotatable cutting blade at the front end of the machine to cut apavement or a slab of concrete beneath the front end of the machine.Conventional concrete cutting machines of this kind typically have apair of front wheels and a pair of rear wheels which may be driven by amotor to move the machine rearwardly or forwardly and a cutting bladelocated on either side of the machine forwardly of the front wheels, thecutting blade being adapted to be rotatably driven from an internalcombustion engine or electric engine mounted on the support structurevia a single belt and pulley drive system.

Conventional concrete cutting machines as described above suffer fromseveral disadvantages. Machines which have the front wheels located at arearward position close to the centre of gravity of the machine arerelatively easy to manoeuvre, but track poorly and require more effortfrom the operator to keep the cutting blade on line if a reasonablecutting speed is to be maintained and many shallow passes can berequired during cutting. Machines with the front wheels located at aforward position close to the cutting blade perform better in the cut,but are heavier to handle and manoeuvre, risking back injury to theoperator. The result, in conventional machines, is a compromise with thefront wheels being located forwardly of the centre of gravity, butbehind the ideal position for cutting.

Conventional machines also suffer from poor stability and poor tractionof the rear drive wheels; for instance, the location of the front wheelsrelatively close to the centre of gravity can result in only one of therear wheels being in contact with the ground and the machine can behaveerratically. The machine may, for example, speed up or slow downirregularly or slide forward into the cut to stall the blade dependingon circumstances such as ground surface conditions, varying hardness ofthe concrete or when the concrete includes reinforcements. Generally,the deeper a machine is into the cut, the less traction is available onthe rear drive wheels due to weight transference. Further, conventionalmachines can easily become unstable on slopes, even on gentle slopessuch as the crossfall of a road.

It is therefore desirable to provide a concrete cutting or sawingmachine which overcomes at least some of above-described disadvantagesof conventional machines and, in particular, a machine which isrelatively easy to manoeuvre and which is very stable in the cuttingmode.

According to one aspect of the present invention there is provided amachine for cutting concrete or like materials comprising a supportstructure carrying ground-engaging rear wheels and at least one frontwheel carried by front wheel support means and being engageable with theground, and rotatable blade means mounted on the support structure at afront end thereof and adapted to be rotatably driven from a motor orengine, characterized in that the machine includes auxiliary wheelsupport means carrying one or more auxiliary wheels at a positionbetween the rear wheels and the at least one front wheel, the auxiliarywheel support means being movable relative to the support structure tolower said one or more auxiliary wheels into contact with the ground andto raise the at least one front wheel above the ground so that theforward part of the support structure is supported upon said one or moreauxiliary wheels.

Whilst the concrete cutting machine of the invention may have a single,centrally mounted front wheel provided on front wheel support means,preferably a pair of front wheels are provided on a common front wheelsupport means with each front wheel being mounted inwardly of-the rearwheels. Preferably, the auxiliary wheel support means comprises atransverse axle carrying a pair of auxiliary wheels, the transverse axlebeing disposed approximately vertically below the centre of gravity ofthe concrete cutting machine.

The inward, forward location of the front wheels provides improvedcutting and stability of the machine in the cutting mode for cuttingconcrete and the disposition of the auxiliary wheels substantially belowthe centre of gravity of the machine greatly facilitates manoeuvering ofthe machine when the front wheels are raised off the ground in themanoeuvering mode. In the cutting mode, both rear drive wheels stay incontact with the pavement, so that during the cut the machine will stayon line more easily requiring less correction by the operator andimproving the quality of the finished cut producing a straighter,smoother cut face. Also, greatly increased stability in the cut enablesthe blade to cut more freely making it possible to cut deeper and fasterper pass.

The front wheel or each front wheel is preferably carried by front wheelsupport means mounted for pivotal movement relative to the supportstructure so as to be movable between a ground-engaging position in thecutting mode and a raised position in the manoeuvering mode, and theauxiliary wheel support means is preferably mounted so as to bepivotally movable relative to both the support structure and the frontwheel support means.

The front wheel support means may be pivotally movable about a differenttransverse axis as the auxiliary wheel support means, but preferably thefront wheel support means and auxiliary wheel support means arepivotally movable about a common transverse axis, and the relativepivotal movements may be effected by any convenient actuating means suchas hydraulic piston and cylinder assemblies; this has the furtheradvantage that the auxiliary wheels follow the movement of the frontwheel or wheels so that the auxiliary wheels do not have to travel asfar between their positions in the cutting mode and the manoeuveringmode. In a preferred embodiment, a first piston and cylinder assemblyextending longitudinally acts between a rear frame member of the supportstructure and the front wheel support means, and a second piston andcylinder assembly extends upwardly from a part of the auxiliary wheelsupport means to act on a part of the front wheel support means.

According to a second aspect of the invention there is provided aconcrete cutting machine for cutting concrete or like materialscomprising a support structure having a rear end and a front end, a pairof ground-engaging rear wheels provided at the rear end of said supportstructure, front wheel support means disposed towards the front end ofsaid support structure, one or more front wheels provided on said frontwheel support means, rotatable blade means provided at the front end ofsaid support structure, a drive motor or engine supported on the supportstructure, and means for transmitting drive from the motor or engine tothe rotatable blade means, characterized in that the machine furthercomprises auxiliary wheel support means and one or more auxiliary wheelsmounted on said auxiliary wheel support means, said front wheel supportmeans being movable relative to said support structure and saidauxiliary wheel support means being movable relative to said supportstructure and relative to said front wheel support means, firstactuating means operable to effect relative movement between said frontwheel support means and said support structure, second actuating meansoperable to effect movement of said auxiliary wheel support meansrelative to said support structure and to said front wheel support meanswhereby the front wheel support means, the auxiliary wheel support meansand the support structure are relatively movable between a firstposition for cutting concrete in which said one or more front wheels arein contact with the ground and the auxiliary wheels are raised above theground and a second position for manoeuvering the machine in which saidauxiliary wheels are in engagement with the ground and said one or morefront wheels are raised above the ground.

A concrete cutting machine incorporating the various aspects of thepresent invention will now be described, by way of example only, withreference to the accompanying drawings, in which:

FIG. 1. is a side view of a concrete cutting machine in accordance withthe invention with the cutting blade in a raised position and the rearand auxiliary wheels arranged for manoeuvering the machine;

FIG. 2 is a partial side view of the machine in a position with theblade about to enter a pavement or concrete slab for cutting; and

FIG. 3 is a plan view of the undercarriage of the concrete cuttingmachine of FIGS. 1 and 2.

Referring to FIGS. 1 to 3 of the drawing there is illustrated a concretecutting machine 10 comprising a support structure or frame 12, a pair offront wheels 14, a pair of rear wheels 16 adapted to be driven by anhydraulic motor of an hydraulic system (not shown) housed within a rearhousing 17 of the machine to move the concrete cutting machine forwardlyor rearwardly, and a rotatable cutting blade 20 disposed at either sideof the machine slightly forwardly of the front wheels 14. The blade 20can be rotatably driven from an engine 18 mounted on the supportstructure 12 via a blade drive transmission system 19 which is describedin more detail in my co-pending International Patent Applicationentitled "Improved Blade Shaft Drive for Machines having Rotary Cuttingor Abrading Tools" the disclosure of which may be considered to formpart of this specification as if it were incorporated herein. The engine18 is also used to drive an hydraulic pump 21 for the hydraulic systemvia a belt drive 23.

As shown in FIG. 3, the support structure 12 comprises a substantiallyrectangular frame having longitudinal side members 22, a front framemember 24, a rear frame member 26 and an intermediate frame member 28extending transversely between the side members 22. Located in front ofthe intermediate frame member 28 is a transversely extending shaft 30which forms a pivot for the front pair of wheels 14 and for a-pair ofauxiliary intermediate wheels 32. The auxiliary wheels 32 are providedon a transverse axle 34 which is connected by a pair of longitudinallyextending support arms 36 to the shaft 30 in such a manner that the arms36 and the axle 34 constitute support means for the auxiliary wheels 32,the auxiliary wheel support means 34 and 36 being pivotally movablerelative to the support frame structure 12 about the axis of the shaft30.

The front wheels 14 are mounted on a transversely extending front axle38 connected to the transverse shaft 30 by longitudinally extendingsupport members 40. The axle 38 and the support members 40 constitutefront wheel support means which is also pivotally movable relative tothe support frame structure 12 about the axis of the shaft 30. Pivotalmovement of the longitudinal members 40, front axle 38 and front wheels14 relative to the support frame structure 12 is achieved by extensionor contraction of a first, longitudinally extending hydraulic piston andcylinder assembly 42, one end of which is connected to the rear framemember 26 and the other end of which is connected to a rod 44 extendingtransversely between the rear ends of the longitudinal members 40 at aposition above and slightly to the rear of the transverse shaft 30.

Whilst the drawings show one end of the piston and cylinder assembly 42connected to the rear frame member 26, in an alternative embodiment (notshown) the piston and cylinder assembly may instead be connected to andextend between any other frame member and a part of the front wheelsupport means.

A second, substantially vertically extending hydraulic piston andcylinder assembly 46 is provided which has an upper end connected to atransverse element 50 extending between the front axle support members40 and a lower end connected to a transverse member 48 connected to andextending between the longitudinal support arms 36. Alternatively, thelower end of the piston and cylinder assembly may be connected to aflange on the axle 34. Extension or contraction of the second piston andcylinder assembly 46 causes the support arms 36 and axle 34 of theauxiliary wheels 32 to move relative to the support members 40, frontaxle 38 and front wheels 14. Control levers 52 and 56 are preferablyprovided at the rear of the machine to effect actuation of therespective first and second hydraulic piston and cylinder assemblies 42and 46.

FIG. 1 of the drawings shows the machine in a manoeuvering position inwhich the operator can grasp a pair of handles 51 extending rearwardlyand substantially horizontally from the rear of the machine and use thehandles 51 to lift the rear wheels clear of the ground or pavement tomanoeuvre the machine easily into the required position for cutting.When the machine is in the required position for cutting the operatoractuates one of the control levers 56 to contract the second piston andcylinder assembly 46 to move the front wheels 14 downwardly intoengagement with the ground. Further contraction of the piston andcylinder assembly 46 raises the auxiliary wheels 32 above the groundinto the position shown in FIG. 2.

FIG. 2 of the drawings shows the concrete cutting machine 10 in acutting mode just prior to the blade entering a pavement or a slab ofconcrete beneath the front end of the machine. In this position thefront and rear wheels 14 and 16 are in engagement with the groundindicated by line A and the auxiliary wheels 32 are raised slightlyabove ground level. In this position the operator stands at the rear ofthe machine where he can control the engine 18 and the blade drivetransmission system 19 to cause the cutting blade 20 to rotate. Theoperator can also control the blade penetration into the pavement byactuating another of the control levers 52 to contract the hydraulicpiston and cylinder assembly 42 so that the support structure 12 pivotsrelative to the support members 40 to move the cutting blade 20 intoengagement with the pavement or concrete slab to the required depth ofcut and the operator can control drive to the rear wheels 16 to move themachine forwardly or rearwardly. The concrete cutting machine may have apair of cutting blades, one on each side of the machine, so that theoperator can choose which of the blades he wishes or needs to use whencutting a slab of concrete. It will, however, be appreciated that thepresent invention is equally applicable to a machine having one concretecutting blade 20 which may be located on either the left or right sideof the machine.

When the operator has finished cutting, he can then operate the controllever 52 to actuate the hydraulic piston and cylinder assembly 42 tolift the blade clear of the pavement. From the position shown in FIG. 2,actuation of control lever 56 extends the second piston and cylinderassembly 46 to move the auxiliary wheels 32 downwardly into engagementwith the ground and to raise the front wheels 14 and the front end ofthe support frame structure 12 above the ground into the manoeuveringposition shown in FIG. 1 in which the machine is supported by theauxiliary wheels 32 and the rear wheels 16. In this position, the centreof gravity of the machine is located at a position almost verticallyabove the auxiliary wheel axle 34 thereby greatly enhancingmanoeuvrability of the machine as compared with some conventionalconcrete cutting machines which have front wheels disposed well inadvance of the centre of gravity and no auxiliary wheels.

From the above description it will be apparent that the presentinvention provides an improved wheels and undercarriage arrangement forconcrete cutting or sawing machines which provides optimum performanceeither when the machine is cutting or when it is being manoeuvered. Theoperator can select either one of two distinctive wheel arrangements. Inthe cutting mode, maximum machine stability is obtained with each rearwheel in contact with the pavement and each rear wheel and the frontwheel or wheels supporting approximately the same weight. In themanoeuvering mode the weight is minimized at the handles, enabling theoperator to handle the machine comfortably. The invention thus providesa greater ease of manoeuvrability for the operator when the machine isout of the cutting mode and better stability and reduced vibrationduring the cutting mode which results in an increased blade life and animproved cut of a better quality finish. It is also possible, whencutting blades of smaller diameters are used, to use the machine forcutting concrete when it is supported on the auxiliary wheels instead ofthe front wheels. This facilitates use of the machine for makingrepeated short cuts, enabling the machine after one short cut to bequickly manoeuvered into the position for the next short cut.

It will be appreciated that various modifications may be made to theconcrete cutting machine as described above without departing from thescope or spirit of the invention. For instance, the pair of front wheelsmounted inwardly close to the longitudinal central axis of the machinemay be replaced by a single centrally mounted front wheel. Also, thepivot providing the transversely extending pivotal axis about which theauxiliary wheel support means is movable need not comprise atransversely extending shaft. Further, the front wheel support meansdoes not have to be pivotally movable relative to the support framestructure about the same pivotal axis as the auxiliary wheel supportmeans.

I claim:
 1. A manually maneuverable machine for cutting concrete or likematerials comprising a support structure carrying ground-engaging rearwheels and at least one front wheel carried by front wheel support meansand being engageable with the ground, and rotatable blade means mountedon the support structure and adapted to be rotatably driven from a motoror engine mounted on the support structure, wherein the rotatable blademeans is mounted on the support structure at the front end of themachine so that the cutting edge of the blade means is disposedforwardly of the at least one front wheel, and the machine includesauxiliary wheel support means carrying one or more auxiliary wheels at aposition between the rear wheels and the at least one front wheel, thefront wheel support means and the auxiliary wheel support means beingmounted for pivotal movement relative to the support structure about acommon transversely extending pivotal axis, the auxiliary wheel supportmeans being movable relative to the support structure to lower said oneor more auxiliary wheels into contact with the ground and to raise theat least one front wheel above the ground.
 2. A machine according toclaim 1 wherein a pair of front wheels are provided on the front wheelsupport means, each wheel of said pair of front wheels being mountedinwardly of the rear wheels.
 3. A machine according to claim 1 whereinthe auxiliary wheel support means comprises a transversely extendingaxle carrying a pair of auxiliary wheels, the auxiliary wheel axle beingdisposed substantially vertically below the centre of gravity of themachine.
 4. A machine according to claim 1, wherein the front wheelsupport means is movable relative to the support structure, and theauxiliary wheel support means is movable relative to the supportstructure and to the front wheel support means.
 5. A machine accordingto claim 1 wherein a first actuating means is provided to effectrelative pivotal movement between the front wheel support means and thesupport structure and a second actuating means is provided to effectpivotal movement of the auxiliary wheel support means relative to thesupport structure and the front wheel support means.
 6. A machineaccording to claim 5 wherein the first actuating means is arranged toact between a frame member of the support structure and a part of thefront wheel support means.
 7. A machine according to claim 5 wherein thesecond actuating means is arranged to act between a part of theauxiliary wheel support means extending forwardly from the pivotal axisand a part of the front wheel support means disposed above the pivotalaxis.
 8. A machine according to claim 5 wherein the first actuatingmeans and the second actuating means each comprises a hydraulic pistonand cylinder assembly.
 9. A machine for cutting concrete or likematerials comprising a support structure having a rear end and a frontend, a pair of ground-engaging rear wheels provided at the rear end ofsaid support structure, front wheel support means disposed towards thefront end of said support structure, at least one front wheel providedon said front wheel support means, handle means at the rear of thesupport structure for manually maneuvering the machine, rotatable blademeans provided at the front end of said support structure and having acutting edge disposed forwardly of said at least one front wheel, adrive motor or engine supported on the support structure, and means fortransmitting drive from the motor or engine to the rotatable blademeans, wherein the machine further comprises auxiliary wheel supportmeans and one or more auxiliary wheels mounted on said auxiliary wheelsupport means, said front wheel support means being mounted for movementrelative to said support structure and said auxiliary wheel supportmeans being mounted for movement relative to said support structure andrelative to said front wheel support means, first actuating meanscomprising a piston and cylinder assembly operable to effect relativemovement between said front wheel support means and said supportstructure, second actuating means operable to effect movement of saidauxiliary wheel support means relative to said support structure and tosaid front wheel support means whereby the front wheel support means,the auxiliary wheel support means and the support structure arerelatively movable between a first position for cutting concrete inwhich said one or more front wheels are in contact with the ground andthe auxiliary wheels are raised above the ground and a second positionfor maneuvering the machine in which said auxiliary wheels are inengagement with the ground and said one or more front wheels are raisedabove the ground.
 10. A machine according to claim 9 wherein said firstactuating means is operable in said first position for cutting concreteto move said front wheel support means relative to said supportstructure to control the depth of cut.
 11. A machine according to claim9 wherein the first actuating means and the second actuating means eachcomprises a hydraulic piston and cylinder assembly.
 12. A machineaccording to claim 9 wherein the front wheel support means and theauxiliary wheel support means are mounted for pivotal movement relativeto the support structure about a common transversely extending pivotalaxis.
 13. A machine according to claim 12 wherein the second actuatingmeans is arranged to act between a part of the auxiliary wheel supportmeans extending forwardly from said pivotal axis and a part of the frontwheel support means disposed above said pivotal axis.
 14. A machineaccording to claim 9 wherein the first actuating means is arranged toact between a frame member of the support structure and a part of thefront wheel support means.